Variable power transmission



April 12, 1949. R PB 2,466,762

VARIABLE POWER TRANSMISS ION 'Filed April 15, 1946 I [NVE TOR. Phi/ '0 5i 6 Patented Apr. 12, 1949 Phillip B. Campbell, Kansas to Phillip D. Campbell, KansasCity,

one -half Mo.

City, Mo., assignor of Application April. 15, 1946, Serial No. 662,367

This invention relates to the art of power transmission and particularly to structure interposable between a drive and a driven shaft to transfer power from the former to the latter and the primary objectis the provision of such equipment wherein is embodied novel and unique means for infinitely varying the speed of the driven shaft. as the drive shaft is constantly rotated by a prime mover.

This invention: has for a, further important aim to provide a variable power transmission having an unique train of gears including a retardable element with which is associated means for electrically braking the said element to vary the speed of the transmission and, therefore, the driven shaft with which the transmission is associated.

A. yet further object of this invention is to provide an infinitely variable power transmission wherein is incorporated magnetic means for cooperating with certain of a number of gears constituting a coupling between a drive and a. driven shaft to vary the speed ratio between the former and the latter, which magnetic means is energized by current from an alternator driven at selected desirable speeds through parts motivated by the drive shaft or by any independent means.

The mode; of operating the elements constituting the variable power transmission and the specific way of constructing and combining the component elements of said transmissionv are of importance and constitute additional objects of the invention, all of which will appear during the course of the following specification refer-- ring to the accompanying drawing wherein is diagrammatically illustrated a variable power transmission made pursuant to my invention.

The transmission chosen for illustration comprises five sections or groups of parts, the first of which includes a. drive shaft ill operably joined to any prime. mover (not here shown), a driven shaft t2 and gears t6 and I8 interconnecting the proximal ends of shafts it]. and I2. A mem-- her It, freely rotatable on drive shaft to has gears 28 on one face thereof in mesh with gears it. The other face 22 of member 54 is an hypoid. member for reasons more fully hereinafter set: down.

A crossarm 24 on drive shaft Ill constitutes a 2 tutes the second important element of the transmission and is joined to the above describedassembly of gears and shafts. by a pair of hypoid gears 3. 5 and 3%, both of which are. in mesh with. hypoid member face 22 of member l4.

Gear 3G, forming a part of the third section ofthe transmission, is rigid to shaft 38 intersectthe axisv of drive shaft 10 to one side thereof. and attached to armature 28 for rotation therewith. I-Iypoid gear 35 is mounted upon a. tubular shaft it circumscribing a portion of shaft 38 and secured to the pole carrying portion 30 of magnetic means 26. Gear 36",. like gear 34; is in. mesh with face 22- of member 14. This magnetic means 2t is similar to a squirrel-cage. induction motor with the armature and pole carrying portion rotating in opposite directions. by virtue of the structure just set down.

The size of gears 3A and 35 is the same and therefore, armature 28 and member 30 of magnetic means 26 will always be rotated at the same speed but in opposite directions by member M when drive shaft lEl-is rotated.

Field coils 32 of magnetic means 26 may be energized by current generated in an alternator 42, joined to field coils 32 of magnetic means 26 by conductors M of known characteristics that:

carry current to slip rings Mi. This generator or alternator 42 is the fourth main element of the variable transmission and supplies alternating current for clutch excitation. The output of generator 42 may be controlled by varying the speed of the generator 42 through the medium; of the fifth. assembly ofparts constituting: a unit.

:2 01 the transmission.

This assembly of parts establishes driving con-- nection between generator 52: and drive shaft l8 and has a disk 48 rigid to drive shaft.- IU. infrictional engagement with a disk of lesser diam.- eter mounted for longitudinal movement along: squared shaft 52 of generator 42; Small disk 56) is shiftable manually by any connection such as lever 5 having means (not shown) for holding the same in selected positions and as the small disk is moved toward and from the axis of drive shaft Hi, the: speed: of generator" 42 will be decreased and increased respectively.

The simple generator drive: just described; is' possible because clutch excitation power required is very small when considering the prime mover power transmitted through drive shaft H]. A low capacity variable drive constituting the parts just defined is satisfactory,

During the normal operation of the transmis-' sion, gears It move in their orbit with. the supporting crossarm 24. If member M- is allowed: to.- turn freely when a load is ondriven shaft t2, power will be transmitted through the chain of gears from drive shaft I 0-. Driven shaft I12 will; therefore, not be actuated and; member M:

rotate freely at twice the speed of drive shaft l0 and power may be transmitted to driven shaft 12 through gear l8 only by retarding the rotation of member I4 and reducing its speed to a point less than twice the rotative speed of drive shaft 10. At the speed of rotation of this member I4 is decreased relative to the speed of rotation of drive shaft 10, the rotative speed of gear l8 and driven shaft I2 is increased. Thus an infinitely variable transmission is obtainable provided the of field coils 32 will serve to control the speed of rotation of member [5. If field coils 32 of magnetic means 3% are energized with alternating current in a manner resulting in the field rotating electrically in a direction opposite to its mechanical rotation, the resulting speed of members 28 and 30 would be maintained at one-half the synchronous speed of the field relative to the field portion of the clutch. Thus, the speed of rotation of member I4 is controlled by varying the clutch excitation frequency. This is done by varying the speed of generator 42 by suitably manipulating disk 50.

A typical example of transmission operation may be tabulated as follows:

Number of poles on the pole carrying portion of magnetic means 26 Prime mover speed or speed of rotation of drive shaft 10 R.. P. M 1000 Gear ratio, hypoid gear 22 to gears 34 and 35 2 to 1 Desired speed of driven shaft l2 R. P. M 300 Magnetic means 28 and 3t rotate in opposite direction at R. P. M 850 Resultant speed of separation of magnetic means R. P. M 1700 In order that the magnetic means may be maintained at the resultant speed of separation of 1700 R. P. M. the revolving field set up in the pole carrying portion 30 of the magnetic means must have a synchronous speed of 1700 R. P. M. relative to the pole portion and in opposite direction to that of the mechanical rotation. This places the revolving field in step with thecenter portion of the magnetic means.

Excitation frequency required is, therefore:

It has been set down above the manner in which this variable frequency may be obtained through the employment of generator 42 and while it has been disclosed to be means for varying the speed of generator 42, it is obvious that varying the number of poles of the alternator or generator supplying the exciting power will accomplish the same result. Electrically loading equals equals portions of the variable power transmission to retard the movement of one of the elements of the assembly is accomplished through employment of the magnetic means 26 and it is the use of such an element in a transmission assembly that permits reaching the efiective and eflioient mode of operation capable of emanating from the transmission above described and diagrammatically shown in the drawing referred to throughout the specification.

It is realized that variable power transmissions having characteristics different from those described and illustrated may be made without departing from the spirit of the invention or scope of the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In a variable power transmission of the character described having a drive shaft and a driven shaft, structure interconnecting the drive shaft and the driven shaft, including a movable element adapted to progressively increase the speed ratio between the drive shaft and the driven shaft as the movement of said element is retarded; magnetic means for retarding the movement of the element; and a generator driven by the drive shaft for supplying current to the said magnetic means, said generator having a variable driving connection with the drive shaft.

2. In a variable power transmission having a drive shaft and a driven shaft, a crossarm 0n the drive shaft having a pair of spaced beveled gears mounted thereon for free rotation, a gear rigid to the driven shaft in mesh with the bevel gears of the crossarm; a member having a pair of opposed, bevel gears integral therewith, said member being mounted on the drive shaft for free rotation, with one of the gears thereof in mesh with the bevel gears of the crossarm; magnetic means having an armature and a pole carrying portion; a pair of hypoid gears in mesh with the other gear of the member; a shaft rigid with one of the hypoid gears and joined to the armature of the magnetic means; a member connecting the other hypoid gear and the pole carrying portion of the said magnetic means; and a generator for energizing the magnetic means.

3. In a variable power transmission having a drive shaft and a driven shaft, 2. crossarm on the drive shaft having a pair of spaced bevel gears mounted thereon for free rotation, a gear rigid to the driven shaft in mesh with the bevel gears of the crossarm; a member having a pair of opposed gears integral therewith, said member being mounted on the drive shaft for free rotation thereon, with one of the opposed gears thereof in mesh with the bevel gears of the crossarm; a pair of spaced hypoid gears in mesh with the other of said opposed gears of the member, said hypoid gears having coaxial axes; and means for retarding the rotation of said hypoid gears whereby to reduce the speed of rotation of said member as the latter is rotated by said drive shaft through said hypoid gears.

4. In a variable power transmission as set forth in claim 3 wherein said means comprises magnetic apparatus having an armature and a pole carrying portion operably connected with each of said hypoid gears respectively, and electrical means tending to rotate the armature and pole carrying portion in opposite directions.

5. In a variable power transmission as set forth in claim 3 wherein said means comprises magnetic apparatus having a rotatable armature joined to one of said hypoid gears and a pole carrying portion rotatably mounted on said armature and joined to the other of said hypoid gears, and a generator so connected electrically to the armature and to the pole carrying portion to tend to rotate the armature and said portion in opposite directions.

6. In a variable power transmission as set forth in claim 3 wherein said means comprises magnetic apparatus having a rotatable armature joined to one of said hypoid gears and a pole carrying portion rotatably mounted on said armature and joined to the other of said hypoid gears, and a generator so connected electrically to the armature and to the pole carrying portion to tend to rotate the armature and said portion in opposite directions, said generator having a rotatable armature and means to vary the speed of rotation thereof, whereby to vary the excitation of said magnetic apparatus.

7. In a variable power transmission having a drive shaft and a driven shaft, a crossarm on the drive shaft having a pair of spaced bevel gears mounted thereon for free rotation; a gear rigid to the driven shaft in mesh with the bevel gears of the crossarm; a member having a pair of opposed bevel gears integral therewith, said member being mounted on the drive shaft for free rotation, with one of the gears thereof in mesh with the bevel gears of the crossarm; magnetic means having an armature, field coils, and a pole carrying portion; a pair of hypoid gears in mesh with the other gear of the member; a shaft rigid with one of the hypoid gears and joined to the armature of the magnetic means; a tubular shaft circumscribing a portion of the last-mentioned shaft and connecting the other hypoid gear and the pole carrying portion of the said magnetic means; a generator for energizing the field coils of the magnetic means with current of desired frequency, said hypoid gears meshing with said other gear of the member and having coaxial axes, whereby said armature and the said pole carrying portion are rotated in opposite directions by the hypoid gears, said field coils being so electrically connected to the generator to cause the resulting magnetic field to rotate counter to the rotation of said pole carrying portion; and means for varying the excitation frequency, of the magnetic means whereby to control the speed of rotation of the member and to vary the speed ratio between the driven shaft and the drive shaft through said hypoid gears and said member.

PHILLIP B. CAMPBELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain May 13,1920

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